Several thousand people gathered on Sunday at the sacred Lake Harsadi near the town of Bishoftu, 40km (25 miles) south of the capital Addis Ababa, to take part in the Irreecha ceremony, Reuters reported. The festivity celebrates the end of the rainy season and is marked by Ethiopian farmers.

The gathering this year had anti-government sentiments, as local farmers accused the authorities of planning to seize their lands to expand the capital. Some protesters waved flags of the opposition Oromo Liberation Front, which the Ethiopian government considers terrorists.

A stand-off with the police degenerated into chaos after protesters pelted security troops, who responded with tear gas canisters and warning shots. The gas triggered panic in the crowd and led to a stampede.

Ethiopia is currently ruled by the Tigrayan People’s Liberation Front, which came to power in 1991 by ousting strongman Mengistu Haile Mariam. The front currently stands accused of monopolizing power in the country. In the 2015 parliamentary election, the opposition lost the only seat it had in the national legislature.